The present disclosure relates to the field of pin tumbler locks and more particularly to a pin tumbler lock having a removable internal core.
Conventional pin tumbler cam locks comprise a core including an annular cylinder and rotary plug. The core is located within a lock housing. The plug has a row of individual tumbler pins slidable toward or away from the plug rotational axis. The annular cylinder has a corresponding row of spring-biased drive pins in registration with the tumbler pins. The drive pins are normally urged partway into the mounting holes for the tumbler pins so that the plug cannot rotate.
In the locked position, a key may be inserted into a key slot in the plug to push the tumbler pins outwardly, thereby moving the drive pins out of the tumbler pin mounting holes. These tumbler pin movements align the outer ends of the tumbler pins to become coincident with the plug outer surface. The plug can be rotated to the open position by turning the key. The plug supports a lock plate that swings behind a keeper to lock or unlock the device.
In a more sophisticated arrangement, a pin tumbler cam lock can have a multiplicity of rows of pin tumblers. The pin tumblers can be arranged in a manner in that a relatively large number of tumbler pins can be accommodated in a relatively small size lock housing. The rotary plug can have a key slot with a narrow rectangular cross-section. The mating key can have two parallel flat side surfaces and two connecting edge surfaces. Rows of conical depressions are defined in the flat side surfaces and the edge surfaces of the key. The plug has three rows of tumbler pins located in the plug in order that the pins register with the conical depressions defined in the key. The pin inner ends are conically shaped in order to mate with the conical depressions on the key.
When the key is inserted into the key slot the depressions in the key locate the tumbler pins at the correct height in the mounting holes. Spring-biased drive pins are mounted in a stationary cylinder surrounding the rotary plug to normally extend partly into the mounting holes for the tumbler pins. The key upon insertion into the plug, moves the tumbler pins outwardly to drive the drive pins out of the plug. With the drive pins free of interference, the plug can rotate freely. There are three rows of tumbler pins extending radially from the pin rotational axis. In some lock arrangements, the pins are arranged in the plug in three rows with one row containing five sets of drive pins and tumbler pins and springs. The other two rows contain six sets of drive pins, tumbler pins and springs. The arrangement has a total of seventeen sets of pins and springs for securing the lock and resisting lock picking.
The plug motion is controlled by a feature known as a stop arm or tab extending from the rear of the stationary cylinder through an aperture in the rear of the lock housing shell. The stop arm cooperates with a stop plate carried on the rotary plug and in registration with the stop arm. The stop arm is designed to limit the rotation of the stop plate in two directions. The plug position is determined by the limitation of the rotation. The plug can be positioned in the locked condition of the lock and the plug can be positioned in the unlocked condition of the lock. The single stop arm determines both end positions of the rotary plug and therefore provides for more accurate control of the plug motion. Manufacturing tolerances and tolerance build-up becomes less of an adverse factor.
The plug control through the stop arm on the exterior of the structure provides for a shorter lock length. This shorter lock length is done without the elimination of pins or tumblers.
The plug in the lock is inserted into an annular cylinder that is covered by a housing sleeve to form the core. The housing sleeve is inserted into a housing shell. The housing shell is typically inserted into a cabinet door and permanently fastened to the cabinet door. The entire lock including the fixed housing shell in the door, the rotatable plug within the cylinder and sleeve combined provide for locking the cabinet door. The housing shell has threaded side surfaces that receive a nut in order to fasten the lock onto the cabinet door. The cabinet has a keeper that is fixed to the cabinet to block the cabinet from opening. The lock has a corresponding lock plate that rotates into locked and unlocked position depending upon the relationship to the keeper on the cabinet. The lock plate is attached to the plug on the end of the plug opposite the key slot. The plug has a threaded stem that receives the lock plate and a nut to threadably tighten and fix the lock plate to the plug. The plug rotates the lock plate into and out of engagement with the keeper on the cabinet.
In order to remove the plug from the housing, the nut holding the lock plate must be removed from the threaded end of the plug. Removal of the nut can only be done when the cabinet door is open and the back of the lock is exposed for removal of the nut and lock plate. With the nut and lock plate removed, the plug, cylinder and housing sleeve, i.e., the core can be removed from within the fixed housing shell in the cabinet door.
In many lock applications, the contents of the cabinet are sensitive to exposure from the external environment, such as dust and moisture from the exterior of the cabinet. In other applications, the contents require security from unauthorized persons and tampering with the contents.
Also in many lock applications, the key for the specific lock becomes lost or must be rekeyed for security purposes. The corresponding pin and tumbler arrangement must be changed to match the new key. The lock plug and cylinder assembly (core) must be removed in order the change the pin and tumbler arrangement for the new key. The resultant problem arises with the need to remove the plug. The cabinet door must be opened creating the above mentioned environmental and security risks.
There have been lock core designs that allow for the removal of the core without the need to open the cabinet door to access the rear of the lock. These prior art locks require plug and cylinder arrangements that are bulky as well as limit the range of rotation of the plug. Additionally, after removal of the core, the replacement core would have realignment malfunctions with the lock plate or cam actuators at the back end of the lock. The weight of the lock plate may cause the lock plate to inadvertently rotate out of alignment with the replacement plug. The plug is also limited to only a left handed turn or limited to only a right handed turn, (clockwise, counterclockwise) so that the lock can only be installed in a cabinet door with the hinges on the left or only installed in a cabinet door with the hinges on the right.
What is needed in the art is a compact lock with a removable plug that can rotate in any direction with full range of rotation that does not require the locked cabinet door to be opened for the removal of the plug as well as a replacement core that will realign in the lock housing with ease.
The disclosed device is directed towards a key operated lock. The key operated lock comprises a barrel defining an interior, the barrel having an alignment block at the interior. A core is insertable into the interior. The core demountably coupling with the alignment block in both a clockwise and a counterclockwise direction.
In another embodiment the disclosed device is directed towards a key operated lock comprising a barrel defining an interior and an exterior, the barrel having a front end and a rear end opposite thereof. The barrel defining an alignment block in the interior proximate to the rear end. A core is demountably insertable in the interior of the barrel. The core comprises an inner inserted rotatable into an outer. A retainer is disposed over the inner proximate to a rear of the inner and inserted rotatable into the outer at a rear of the outer. A sleeve is disposed over the outer and configured to retain a plurality of drive pin and spring sets disposed through the outer. The plurality of drive pin and spring sets being in operable communication with a corresponding tumbler pin disposed through the inner, wherein the retainer demountably couples with the alignment block in both a clockwise and counter-clockwise direction.